Manatees
on Land?
Manatees seem so perfectly designed for their slow, gentle life in the
water. But can you believe they weren't always that way? Can you believe
that once, long ago, the manatee's ancestors were land animals?

It's
true. Manatees and their closest relative, the dugongs, are in the Order
Sirenia. The term "Sirenia" is derived from the word "siren"
which refers to mermaid-like creatures that stories say the sailors
of long ago saw at sea (including Christopher Columbus.)

Despite
their name, and despite having some similarities to the general body
shape and habitat of other marine mammals (like sea lions, walruses
or dolphins), manatees are not related to
other marine mammals at all. Scientists say there is no "evolutionary
relationship" between manatees/dugongs and marine mammals.

Don't
Forget the UngulateSo
what other species did manatees evolve from? It is believed that manatees
and dugongs evolved from four-footed land mammals over 60 million years
ago, and some scientists believe Manatees evolved from a wading, plant-eating
animal. Believe it or not, but the manatee's closest living relatives
are actually three land animals which include the elephant,the hyrax
(a small, gopher-sized mammal), and the aardvark!.

These four species--manatees, elephants,
hyraxes and aardvarks--are referred to as "subungulates",
meaning they all evolved from a primitive "ungulate" ancestor.
An "ungulate" refers to a hoofed mammal, and includes the
species in the former order ungulata,
such as horses, cattle, deer, swine and elephants. Their common evolutionary
background has been studied using biochemical analysis of proteins.

The earliest animal that had a manatee-like
appearance is thought to be the Potamosiren,
which dates from about 15 million years ago. At that time, that animal
did not have the continual tooth replacement adaptation.

Try
This! Journaling Questions:

Although the manatee is related to the elephant and hyrax and the
aardvark, they are quite different animals. Think about all the parts
and functions of each species' body, and then compare and contrast
them. What similarities are there? What differences are there?

Who are
your family relatives? Do you look like them? How? In what ways are
you different? In what ways are you similar?